In so-called hot-fill packages, a container is filled with hot fluid product and capped while the fluid product is still hot. As the fluid product cools, a reduction in fluid volume creates a vacuum within the package—i.e., an internal pressure that is less than the surrounding atmospheric pressure. When the container is of molded plastic construction, the container wall tends to distort inwardly as the fluid cools. It has been proposed to provide vacuum panel areas on the container wall for controlling the areas of distortion under vacuum. These vacuum panels conventionally are placed in the body portion of the container over which a label subsequently is applied, causing the label undesirably to “crinkle” in a user's hand because of the absence of contact and adhesion entirely around the container wall. It is a general object of the present invention to provide a plastic container and a method of making such a container that are particularly well adapted for use in hot-fill applications, and/or in which vacuum panels are provided in the container wall in an area separate from the label application area, and/or in which the vacuum panels lend an ornamental appearance to the container as a whole, and/or in which the label application area is as large as that of a comparable glass container.
The present invention embodies a number of different aspects, which may be implemented separately from or more preferably in combination with each other.
A blow molded plastic hot-fill container in accordance with a first aspect of the invention includes at least one vacuum panel for inward flexure under vacuum after the container is hot-filled and capped. The vacuum panel is externally concave as viewed in cross section from a first direction and externally convex as viewed in cross section from a second direction orthogonal to the first direction. The at least one vacuum panel preferably is disposed in a sidewall of the container, which preferably is of generally uniform wall thickness, and preferably includes an array of vacuum panels angularly spaced around an axis of the container.
A blow-molded plastic hot-fill container in accordance with a second aspect of the invention includes a base for supporting the container, a body extending from the base, a dome extending from the body and a neck finish extending from the dome. The dome includes an array of vacuum panels, with each of the vacuum panels being externally concave as viewed in cross section from a first direction and externally convex as viewed in cross section from a second direction orthogonal to the first direction. In the preferred embodiment of the invention, the vacuum panels are externally concave as viewed in cross section laterally of the dome, and externally convex in cross section as viewed axially of the dome. The dome, including the array of vacuum panels, preferably is of generally uniform wall thickness, and the vacuum panels preferably have longitudinal axes at acute angles to the central axis of the container neck finish.
A blow-molded plastic hot-fill container in accordance with a third aspect of the invention includes a base for supporting the container, a body extending from the base, a dome extending from the body and a neck finish extending from the dome. The dome includes an array of flexible resilient vacuum panels, with each of the vacuum panels being externally concave as viewed in cross section from a first direction and externally convex as viewed in cross section from a second direction orthogonal to the first direction. The dome, including the array of vacuum panels, preferably is of generally uniform wall thickness and circular in cross section. The body of the container is of cylindrical construction, and includes axially spaced lands for applying a label to the container. Thus, the label is applied to the generally cylindrical body of the container while the vacuum panels are disposed in the dome of the container, so that the label does not overlie the vacuum panels and does not “crinkle” when gripped by a user.
A fourth aspect of the present invention contemplates a method of blow molding a plastic container in accordance with any of the first, second and third aspects of the invention.